PharmPK Discussion - Intra-subject variation calculation

On 6 Mar 2007 at 10:41:40, "Wichittra Tassaneeyakul" (wichitt.at.kku.ac.th) sent the message

The following message was posted to: PharmPK

Dear All,

If we conduct the BE study using 2 way crossoverdesign and from ANOVAresults some say that we could calculate the intra-subject variation.Could you please tell me thw way to calculate it which MS errorshould weuse (from Sub(seq)???). Another point is how to calculate the 90%Confidence interval from Geometric mean, can we use Excel software?

On 6 Mar 2007 at 12:47:52, "Nand Kishore Rawat" (Nand.KishoreRawat.-at-.ranbaxy.com) sent the message

The following message was posted to: PharmPK

Dear Wichittra,

while calculating ANOVA for two-way cross over design,PK ParametersCmax,AUC's are calculated usingmixed effect ANOVA model using Type III sum of squares and taking into consideration different factorsresponsible for variation. These factors are tested at differentlevel of significance depending uponlevarge of factors.

Intra Subject variability is nothing but it is considered as residualvariability after accounting for variabiltybetween treatment,period and subject and it is a major determinant tocalculate estimated sample size.

for calculating 90% CI following procedure is adopted

90% confidence interval for the ratio of the test and referenceproduct averages (least square means) arecalculated using the 90% confidence interval for the differences inthe averages (arithmetic means) of thelog-transformed data and then taking the antilog of the obtainedconfidence limits

we can use Excel for calculating 90% CI, But performing ANOVA inExcel,does not provide more detailed summaryoutputs as compared to SAS and other statistical softwares.

On 6 Mar 2007 at 08:59:53, "Peter Bonate" (peter.bonate.-a-.gmail.com) sent the message

Which error term to use depends on which SAS proc you use. If youuse GLM then use subject nested within sequence as the error term.If you use the Mixed procedure, you use the true error term from themodel.The geometric mean can be calculated as first taking tha natural logof the data then calculating the arithmetic mean of the natural logtransformed data. The arithmetic mean is then exponentiated. Thisis the geometric mean.Good luck,pete bonate

On 6 Mar 2007 at 20:07:04, helmut.schuetz.-at-.bebac.at sent the message

The following message was posted to: PharmPK

Dear Wichittra!

You wrote:

>If we conduct the BE study using 2 way crossoverdesign and from ANOVA >results some say that we could calculate the intra-subject variation. >Could you please tell me thw way to calculate it which MS error >should we use (from Sub(seq)???). >

Yes.CV-intra = sqrt(exp(MSE)-1)

>Another point is how to calculate the 90% >Confidence interval from Geometric mean, can we use Excel software? >

Funny, we had this today ;-)Have a look at this thread:http://forum.bebac.at/mix_entry.php?id=559

On 12 Mar 2007 at 12:12:23, HDesai.aaa.wockhardtin.com sent the message

Dear Wichittra,

You wrote:

>If we conduct the BE study using 2 way crossoverdesign and from ANOVA >results some say that we could calculate the intra-subject variation. >Could you please tell me thw way to calculate it which MS error >should we use (from Sub(seq)???).